1. Field of the Invention
The present invention relates to a data processing system applied in an audio data synthesis system for sequentially processing a first predetermined number of audio data to cumulatively synthesize a digital audio signal in a handheld apparatus (e.g. mobile phones).
2. Description of the Prior Art
Conventional mobile phones comprise two kinds of main functions: 1. for listening, speaking, and data transmission (operated by GSM, GPRS, and CDMA systems); 2. multimedia applications (e.g. Game, MIDI, music, and digital camera). Multiple new functions have been developed with the development of mobile phones to this day. Taking GSM and GPRS as an example, one of the most popular applications is the multimedia message. The Multimedia Message Service (MMS) can send messages comprising multimedia contents, such as every kind of colored pictures, animation cartoons, and sounds (including common rings, chord rings, common sounds, and even an audio segment pre-recorded by the communication device, all depending on the support level of different communication devices). If the network transmitting speed allows, even movie clips can be transmitted. On the other hand, conventional short message service (SMS) can only transmit a few words or basic graphs.
Although MMS can make the message contents more lively and plentiful, MMS needs to use more powerful and efficient device and technology to perform; the wavetable synthesis of music signals is one of the technologies. The technology is an electronic synthesis technology that samples all kinds of instrumental sounds, digitalizes them to musical instrument data, and then stores the sounds in the synthesizing chips (or storing to disk files). Later, when synthesizing a music file, the musical instrument data that corresponds to every music file is selected and simulated; then, the musical signals corresponding to this music file are synthesized. Each musical instrument data comprises a plurality of music data, and the micro processor of the communication device co-operates with the wavetable music synthesizing system to synthesize the musical signals and re-send the musical sounds.
However, in conventional mobile phones, the micro processor already consumes most of its processing ability on listening, speaking, and data transmission. Therefore, the conventional dual micro processor system of mobile phones has been developed for the multimedia applications; the two processors are connected by a processor bridge, and the processor bridge is a dual-port memory or a register file.
The hardware managed by each micro processor is independent from each other; for example, each micro processor manages its own program memory and the data memory of the system. The program memory has the function of executing and temporarily storing a program. The data memory is used for storing system data. However, this method causes some problems: 1. wasting the hardware resource and cost of production; 2. not increasing the processing efficiency; 3. making the system more complex. This design can also be plugged with more processors in the system; however, more processors only cause the system to be more complex and increase the cost of the system substantially.
Prior arts also provide solutions for solving the problem that conventional wavetable synthesis system consumes too much processor resources in personal computers (PC). For example, U.S. Pat. No. 5,753,841 discloses an audio processing device that comprises the digital signal processor (DSP) and can be applied in a PC. The audio data are stored in the system memory of the PC, which only transmits parts of the audio data that are needed by the DSP. The DSP reads from the cache memory and processes a segment of the audio data into a segment of the digital audio signal; and when that process finishes, the DSP processes another segment of the audio data. Each segment of the processed digital audio signal is stored in the cache memory. When the digital audio signal of the whole piece of music has been stored cumulatively, the cumulated signal is transmitted from the cache memory to the external digital/analogy converter. Because the DSP of this invention directly processes the audio data via the peripheral connecting interface (PCI), without using a specific hardware to accelerate the process, a large portion of the DSP processing ability is consumed. If this invention is used on compact mobile phones with limited processing ability, the simple DSP would not be able to process large audio data calculations. Beside mobile phones, other handheld apparatus such as PDAs, palmtop PCs, or smart phones with the personal information management (PIM) function have similar problems when processing the digital audio data because the calculating ability is limited.